Novel catalytic materials for cascade reactions

Abstract

Biomass represents an environmental and economically sustainable industrial feedstock for chemical and fuel production, with considerable interest in developing novel catalysts for its valorisation. Gamma-valerolactone (GVL), derived from glucose via the platform chemicals levulinic acid (LA) and 5-hydroxymethylfurfural (HMF), is a highly desirable compound with potential as both a green solvent and biofuel precursor. This process requires catalytic control of the reaction pathway, as three distinct active sites are required for the full transformation to occur. To study these multistep pathways and develop catalyst that can perform these processes in a cascade, the process got trimmed to the study of HMF to levulinic acid by hydration and the study of levulinic acid to GVL by hydrogenation. The first process will require the use of solid acid catalysts, of which supported sulphonic acid has been selected due to its acidity and ease of synthesis being optimal for this process. To control the reaction, the support was modified across a series of structures to allow or hinder the diffusion of HMF through the structure. The hydrogenation of levulinic acid to GVL has been studied for noble and non-noble metal catalysts, with Ru being indicated as the best performing catalyst for this process. While performing the synthesis, it was discovered that Ru sintered into crystals of 70 nm, which for an expensive noble metal was not optimal. With the addition of ethylene glycol, this sintering was prevented. Synchrotron based studies were performed to understand how ethylene glycol influenced particle growth and prevented the sintering. Both the solid acid and the Ru catalyst performed well when compared against literature, the latter reacting with similar TOFs to reports while at milder conditions. These two catalysts have been combined in a hierarchical compartmentalized core-shell structure, leading to the production of GVL from HMF in a cascade in a single pot successfully.

Date of Award	1 Aug 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Christopher Parlett (Supervisor) & Arthur Garforth (Supervisor)